The present invention relates to a process and an apparatus for the desulfurizing of iron melts.
It has been known for decades how to desulfurize by adding, with the aid of suitable device, substances which are capable of forming compounds with the sulfur contained in the melts at high temperatures and under reducing conditions, these compounds then settling in the slag layer which is present above the melts. Such substances are, for instance, CaSi, CaC.sub.2, or mixtures of CaO and CaF.sub.2.
It has been found that the known desulfurizing processes allow desulfurizing an iron melt containing about 0.025% S, down to 0.012% S, i.e. to reduce the sulfur content by half. This halving of the sulfur content by means of conventional processes can, however, not be achieved when the initial sulfur content is already of the order of about 0.015%.
Conditions are such that the desulfurizing quotient (% S initial/% S final) will drop with the lower initial sulfur content, and that, with the known processes, an initial sulfur content of about 0.015% S can be reduced only to about 0.010%. It is to be noted herein that this cannot be considered a satisfactory result, also not in respect of the desulfurizing effectiveness (% S removed/kg desulfurizing agent).
It is to be emphasized at the same time that desulfurized contents of 0.010% S that can be achieved from an initial 0.015% S by means of conventional processes, will not satisfy the metallurgist in view of the demands for ever lower sulfur contents in the steel.